Ahmad A. Sorour

Thiosemicarbazide and thiocarbohydrazide functionalized chitosan as ecofriendly corrosion inhibitors for carbon steel in hydrochloric acid solution

Organically functionalized chitosan macromolecules namely Chitosan-Thiosemicarbazide (CS-TS) and Chitosan-Thiocarbohydrazide (CS-TCH) were synthesized and evaluated as new corrosion inhibitors for mild steel corrosion in 1M HCl. The FTIR and 1H NMR studies confirmed the formation of the derivatives. The corrosion tests were performed using weight loss method, electrochemical measurements, surface morphology (AFM), quantum chemical investigation and molecular dynamics simulation methods. The maximum efficiency of 92% was obtained at a concentration as low as 200mgL-1. The inhibitors were found to obey Langmuir adsorption isotherm and exhibited both physical and chemical adsorption. Electrochemical impedance spectroscopy (EIS) results showed an increase in polarization resistance which supported the adsorption of inhibitors on the mild steel surface. Tafel data showed a mixed type behavior with cathodic predominance. The data of quantum chemical calculations and molecular dynamics simulation supported the experimental findings.

Effect of Sandblasting on Tensile Properties, Hardness and Fracture Resistance of a Line Pipe Steel Used in Algeria for Oil Transport

Transport of oil and gas through pipelines in the harsh conditions of the Algerian desert, results in erosion of the pipeline materials. Erosion is a mechanical process that causes a loss of wall thickness, damage and residual stresses on the surface of a pipe due to shocks between sand particles and structure surface. Damage manifests by spalling craters of different shapes and depths. The evaluation of tensile properties and hardness after sandblasting for different durations has been performed on API 5L X70 pipeline steel. Particular attention has been paid to fracture resistance after sandblasting to provide the necessary data for defect assessment, specially the effect of sandblasting on the Material Failure Master Curve (MFMC). The results demonstrated that the sandblasting has slightly increased the yield stress, the ultimate strength and the fracture toughness and, at the same time, had an adverse effect on elongation, young’s modulus, hardness and thickness of the tested pipeline.

Efficiency of Green Inhibitors Against Hydrogen Embrittlement on Mechanical Properties of Pipe Steel API 5L X52 in Hydrochloric Acid Medium

The impact of environment can cause many types of degradations such as pitting corrosion, stress corrosion cracking and sulphide stress cracking of metal structures. One of the serious problems of oil extracting industry is the corrosion process. Recently, there were a number of resource failures caused by internal corrosion phenomena recorded in oil and gas industry; the reports confirmed that the failures were due to the effect of traces amounts of Hydrochloric acid. The objective of this study is to use the plant extracts as corrosion inhibitors for API 5L X52 steel. Indeed, these natural extracts contain many families of natural organic compounds “Green”, readily available and renewable. The conducted mechanics tests in this study in the presence of green inhibitors of plant origin will give very promising results on the fracture mechanics properties. The importance of this area of research is to be attributed to the fact that natural products can replace the currently used toxic organic molecules that are condemned by the world directives for using environmentally unacceptable inhibitors.

The Inspections, Standards and Repairing Methods for Pipeline with Composite: A Review and Case Study

The paper inspect, in the first part, some points of view on the burst pressure standards calculation on pipeline with external corrosion defect, a real test will be present. A comparison on the two methods to repair a pipeline will be the focus on the second part. FEM simulation is a good tool to estimate the safety factor on both parts. In the second part of this study, a control of the made reinforcement calculation (thickness of the monchon to be installed) will be given in detail according to the characteristics of the pipe, the composite material and the dimensions of the defect to be repaired. The method of calculation is known and is set out in the two standards which are available. The real question is explaining the hypotheses which are the basis of the equations developed, and to identify the possible limits of the method. On the other hand, to confirm for a judiciously chosen case, this analytical calculation by a finite element calculation and to identify and compare the different composite materials currently available in the industry.

Microstructure and densification of gas atomised Fe–Cr–B based alloy powder consolidated by spark plasma sintering

Abstract This paper is a study of microstructure and densification of a gas atomised Fe–45Cr–5.9B–2Si–0.1C (wt-%) alloy powder consolidated using the spark plasma sintering (SPS) process. The results showed that the fabricated alloy contained about 65 wt-%(Cr,Fe)2B plates and 1 wt-%(Cr,Fe)7C3 precipitates dispersed in a 34 wt-% body centred cubic Fe based solid solution matrix containing Cr and Si. The powder was fully densified with solid state sintering for a short period of time (<10 min). After sintering, the phases did not transform, and the fraction, shape and aspect ratio of (Cr,Fe)2B did not change. In addition, we adapted the known SPS constitutive densification model from Olevsky and Froyen to include a microstructure factor describing deformation of a metal matrix composite powder. The model was in reasonable agreement with the experimental results.

Investigation on the Controlled Degradation and Invitro Mineralization of Carbon Nanotube Reinforced AZ31 Nanocomposite in Simulated Body Fluid

Magnesium (Mg) based implant materials are believed to be the perfect candidates for biomedical applications due to their versatile properties. However, regulating their corrosion/degradation rate in the biological surroundings is still a noteworthy task. Suitable strategies to overcome this task is to wisely select alloy elements with improved corrosion resistance and mechanical characteristics. An attempt has been made to enhance the corrosion and biocompatibility performance of magnesium alloy AZ31 containing carbon nanotubes (CNTs) as reinforcement and evaluate its degradation and invitro mineralization performance in physiological medium. Corrosion behavior of AZ31 alloy with CNTs reinforcement was investigated using electrochemical methods, weight loss, and hydrogen evolution in SBF during short and long-term periods. The obtained results revealed that the corrosion resistance of AZ31 alloy enhanced significantly due to the incorporation of CNTs. Hydrogen evolution test and weight loss tests revealed that the presence of CNTs improves the stability of the Mg(OH)2 and efficiently regulate the degradation behavior in SBF. Surface characterization after immersion in SBF revealed the rapid formation of bone-like apatite layer on the surface, validated a good bioactivity of the AZ31 nanocomposite samples.

The role of the hydrolysis and zirconium concentration on the structure and anticorrosion performances of a hybrid silicate sol-gel coating

AbstractIn sol-gel chemistry, hydrolysis is the key step in the formation of the reactive hydroxide groups that are responsible for the formation of inorganic networks via the occurrence of condensation reactions. Though previous studies have investigated the effect of the hydrolysis conditions on the structure of organically modified silicates (ormosils), no study, to our knowledge, has investigated this variable on the structure of hybrid materials prepared by combinations of an ormosil and a transition metal (TM). Here, we propose to investigate this effect in a hybrid material composed of 3-trimethoxysilylpropylmethacrylate and a zirconium complex. To also highlight the effects of the precursor’s concentrations on the hydrolysis and condensation reactions of the hybrid materials, their relative content was altered along with the hydrolysis degree. The anticorrosion barrier properties were identified by characterisation of coatings deposited on AA2024-T3 substrates and correlation between the structure and the anticorrosion properties of the coatings were performed based on results obtained from structural characterisations (DLS, FTIR, 29Si-NMR, DSC, AFM and SEM) and corrosion testing (EIS and NSS). It is demonstrated that competition in the formation of siloxane and Si-O-Zr bonds takes place and can be controlled by the degree of hydrolysis and the concentration of the zirconium complex. This effect was found to dramatically alter the morphology of the coatings and their subsequent anticorrosion performances. At short-term exposure times, it is found that the most condensed materials exhibited a higher corrosion resistance while over longer periods the performances were found to level. This article highlighted the critical impact of the hydrolysis degree and zirconium concentration on the connectivity of hybrid sol-gel coatings and the impact this has on corrosion performances.

Exploration of Dextran for Application as Corrosion Inhibitor for Steel in Strong Acid Environment: Effect of Molecular Weight, Modification, and Temperature on Efficiency

The possibility of utilizing dextran as a green corrosion inhibitor for steel in strong acid environment was explore using weight loss, electrochemical (electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), potentiodynamic polarization (PDP), and linear polarization (LPR)) supported with surface analysis via scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) techniques. The effect of molecular weight, temperature, and modification on the inhibition efficiency of dextran was also studied. Results from all the applied techniques reveal that dextran exhibit moderate anticorrosion property toward St37-2 steel dissolution in 15% H2SO4 solution. Dextran with molecular weight of 100 000-200 000 g/mol (Dex 1) exhibited the highest inhibition efficiency of 51.38% at 25 °C. Based on PDP results, dextran behaved as a mixed type corrosion inhibitor. Inhibition efficiency of dextran varies inversely with molecular weight but directly with temperature. Two modification approaches, namely incorporation of silver nanoparticles (AgNPs) into dextran matrices and combination with 1 mM KI were adopted to enhance the inhibition efficiency of dextran and the approaches proved effective. The protective capability of Dex 1 has been upgraded from 51.38% to 86.82% by infusion of AgNPs and to 94.21% by combination with KI at 25 °C. Results from the study on the effect of temperature reveals that Dex 1 + KI mixture could synergistically offer 99.4% protection to St37-2 steel in 15% H2SO4 environment at 60 °C. Surface analysis results confirm the presence of additives molecules on the studied metal surface. XPS results disclose that AgNPs are in oxide form while iodide ions are in the form of triiodide and pentaiodide ions on the metal surface. Modified dextran is a promising candidate for application as corrosion inhibitor in acid induced corrosive environment.